Multi-level free energy simulation with a staged transformation approach

Area of Science:

• Computational Chemistry
• Theoretical Chemistry
• Physical Chemistry

Background:

• Multi-level free energy simulations combine computational accuracy and efficiency for condensed phase studies.
• Achieving convergence in these simulations is challenging due to poor distribution overlap between different theory levels.

Purpose of the Study:

• To develop an alternative strategy for enhancing distribution overlap in multi-level free energy simulations.
• To enable staged conversion between low and high levels of theory with improved convergence.

Main Methods:

• Identify degrees of freedom causing distribution gaps between theory levels.
• Treat identified degrees of freedom using constraints, restraints, or intermediate models.
• Perform staged conversion from low to high levels of theory, ensuring favorable distribution overlap.

Main Results:

• The proposed method ensures favorable distribution overlap during the conversion process.
• Free energy components are evaluated explicitly, allowing meaningful comparison to rigorous calculations.
• Additional calculations at the low level of theory minimize computational cost.

Conclusions:

• The staged approach effectively addresses convergence challenges in multi-level free energy simulations.
• This method offers a computationally efficient way to achieve accurate free energy calculations.
• The approach is validated with solution examples, providing insights into reliability factors.